TheDeparted
03/06/2007, 08:51 AM
Found this on a deep sea fishing forum.. wow..
To keep the Tuna in best condition be careful how you handle it.
**Always gaff in head to avoid puncturing flesh which will ruin the meat around the puncture for a good distance.
At the very minimum tuna must be killed and bled immediately to prevent build up of lactic acid and to prevent the temperature of the blood from rising.
STEP 1: If possible, club the fish sharply on the top of the head between the eyes to stun it and prevent the thrashing which bruises the meat.
STEP 2: By running your thumb along the top of the head of the tuna you will feel a soft spot usually directly above the eyes. Insert a sharp spike or knife into this soft spot at an angle of 45°. This is where the brain is. If you hit the spot correctly, the tuna will shudder and the mouth will drop open. Move the spike around to destroy the brain. Another step called the Tanaguchi Method also sees a large diameter length of monofilament run along the backbone to neutralise the nervous system. This stops blood from pumping deeper into flesh.
STEP 3: Lift the pectoral (side) fins and measure about 4 fingers from the base of the pectoral fin. Cut an incision about 2cm long vertically. Blood should flow freely from the cut. Do both sides. It's a good idea to tail rope your tuna and secure it to a cleat over the side before you do this. There is lots of blood and it makes a hell of a mess. Do not bleed by cutting anywhere else.
STEP 4: After 5 to 10 minutes, the bleeding should have stopped. At this point cut out the gills from the underside of the fish leaving the head intact. From inside the gill cavity you can cut into the gut cavity and remove the entrails. You will need to cut a circle around the anal opening to get all the entrails. Do not gut by slicing down the underside and ruin the belly meat. The fish should now be placed into an ice slurry to preserve the flesh.
Keep in mind that only tuna prepped this way with the Tanaguchi rod left in place will be considered Sushi quality. Do not drop fish on deck at any time during handling. Meat bruises very easily and you can tell the difference between bruised flesh and properly handled flesh. Contrary to popular belief Sushi quality tuna is not "caught that day fresh" it has probably been slurried and then frozen for a good week. If someone offers you tuna they caught today as sushi turn it down. It has not been prepared properly. The cold acts on the flesh to preserve and kill off bacteria.
Cutting it up you should quarter it. The fish will have the same vertical backbone as other fish but also a smaller horizontal one along the lateral line/skin color change to use as reference for cutting. Trim off all the dark meat and DO NOT WASH FLESH WITH WATER....JUST WIPE IT CLEAN.
To keep the Tuna in best condition be careful how you handle it.
**Always gaff in head to avoid puncturing flesh which will ruin the meat around the puncture for a good distance.
At the very minimum tuna must be killed and bled immediately to prevent build up of lactic acid and to prevent the temperature of the blood from rising.
STEP 1: If possible, club the fish sharply on the top of the head between the eyes to stun it and prevent the thrashing which bruises the meat.
STEP 2: By running your thumb along the top of the head of the tuna you will feel a soft spot usually directly above the eyes. Insert a sharp spike or knife into this soft spot at an angle of 45°. This is where the brain is. If you hit the spot correctly, the tuna will shudder and the mouth will drop open. Move the spike around to destroy the brain. Another step called the Tanaguchi Method also sees a large diameter length of monofilament run along the backbone to neutralise the nervous system. This stops blood from pumping deeper into flesh.
STEP 3: Lift the pectoral (side) fins and measure about 4 fingers from the base of the pectoral fin. Cut an incision about 2cm long vertically. Blood should flow freely from the cut. Do both sides. It's a good idea to tail rope your tuna and secure it to a cleat over the side before you do this. There is lots of blood and it makes a hell of a mess. Do not bleed by cutting anywhere else.
STEP 4: After 5 to 10 minutes, the bleeding should have stopped. At this point cut out the gills from the underside of the fish leaving the head intact. From inside the gill cavity you can cut into the gut cavity and remove the entrails. You will need to cut a circle around the anal opening to get all the entrails. Do not gut by slicing down the underside and ruin the belly meat. The fish should now be placed into an ice slurry to preserve the flesh.
Keep in mind that only tuna prepped this way with the Tanaguchi rod left in place will be considered Sushi quality. Do not drop fish on deck at any time during handling. Meat bruises very easily and you can tell the difference between bruised flesh and properly handled flesh. Contrary to popular belief Sushi quality tuna is not "caught that day fresh" it has probably been slurried and then frozen for a good week. If someone offers you tuna they caught today as sushi turn it down. It has not been prepared properly. The cold acts on the flesh to preserve and kill off bacteria.
Cutting it up you should quarter it. The fish will have the same vertical backbone as other fish but also a smaller horizontal one along the lateral line/skin color change to use as reference for cutting. Trim off all the dark meat and DO NOT WASH FLESH WITH WATER....JUST WIPE IT CLEAN.